Parr .— The Response of Pilobolus to Light. 187 
IV. Experimental Data and Results. 
In Table II the measurements of wave-lengths as determined on 
a Hilger spectrometer for the Nernst and the nitrogen-filled tungsten 
Mazda lamps used in these experiments are given. 
Table II. 
Nernst. Tungsten. 
Colour. 
Included wave¬ 
Mean wave¬ 
Included wave¬ 
Mean wave¬ 
lengths. 
length. 
lengths. 
length. 
Red 
704 
708 
725 
708 
712 
691 
SJ 
695 
667 
692 
666 
638 
635 
Orange 
647 
631 
653 
631 
616 
610 
99 
660 
612 
640 
611 
564 . 
581 
Yellow 
625 
5 8 9 
603 
589 
553 
576 
»> 
6 79 
585 
609 
583 
55 1 
5.58 
Green 
570 
54° 
552 
538 
510 
525 
99 
543 
5 2 5 
54 3 
523 
5°7 
503 
Blue 
510 
496 
570 
498 
482 
486 
Si 
479 
470 
490 
473 
461 
45 6 
Indigo 
47 2 
465 
468 
464 
458 
459 
99 
444 
438 
442 
437 
432 
43i 
Violet 
430 
4*4 
420 
4i5 
408 
410 
u 
410 
398 
408 
398 
385 
388 
Table III gives the data for the galvanometer deflexions produced by 
the Hefner lamp at a distance of 2 metres, and for the red region of the 
Nernst lamp. The energy value of the red region of the Nernst lamp was 
calculated from the Angstrom value of the Hefner. 
Table III. 
Light 
source . 
Colour. 
Wave-length . 
Galvanometer deflexion 
in mm. 
Hefner 
lamp 
Nernst Red 
lamp 
Total radiation 
at 2 metres 
+ 667 
540- 70 = 470 
530- 90 - 440 
510 - 70 - 440 
520- 70 = 450 
603-365 = 238 
595-350 --= -2 45 
600-350 = 250 
590-370 = 220 
Average deflexion tf. 
in mm. ' % 
450 2*075 
238 1*097 
